The popular event attracts about 35,000 to the Belchertown town common.

The Sept. 20 fireworks are postponed until a later date that has not been determined.

Officials said the risk of exposure is too great to allow the fireworks, because they are set off near wetlands that are known breeding grounds for EEE.

Metcalf urged the fair committee to set up mosquito killing mechanisms on the town common and to consider localized spraying. She said the location of the fair, on higher, drier ground, poses a much lower risk to the public for EEE than the fireworks location.

The Board of Health said an elderly horse, located in Belchertown had to be euthanized. They said EEE was detected in the infected horse on Thursday, September 6 and that initially the diagnosis was thought by some to be rabies.

Metcalf said the EEE “has a very fast onset, like this girl up in Athol.”

“We are in the inner circle of critical,” health board chairman Gail Gramarossa said. She said the “critical” danger label applied by the state is the most extreme and that consequently the state Department of Public Health said the designation means the local health panel has the authority to declare a health emergency should they see fit.

Gramarossa said more than half of those who contract EEE die and survivors can suffer severe brain and neurological damage.

The board of health said that instead of declaring an emergency -- and mandating restricted activity -- they are urging residents to use common sense, avoid exposure to mosquitoes when risk is highest in the evening, and to wear repellent.

In response to a question for a resident attending the meeting, Police Chief Francis Fox said his department would not enforce outdoor restrictions – unless the health board decided to declare an emergency – which they have not done.

“The first thing is prevention and public education,” the chief said. Exposing oneself to danger “is at your own risk,” he said.

Metcalf said the state has no mosquito traps in town that could collect samples to provide evidence showing if other infected bugs are flying around.

She said Northampton is the only community in Hampshire County where mosquito samples are collected.